と(to) — And (Exhaustive), With, and Quotation

• パンと卵を買います。

  Pan to tamago o kaimasu.

  I buy bread and eggs.

  パン (bread) と (and) 卵 (eggs) — an exhaustive list, nothing else was bought

• 家族と日本へ行きました。

  Kazoku to Nihon e ikimashita.

  I went to Japan with my family.

  家族 (family) と (with); 日本 (Japan) へ (toward)

• 「美味しい」と言いました。

  "Oishii" to iimashita.

  She said, "It's delicious."

  と packages the quoted phrase for the verb 言う (say), like quotation marks

• ・Exhaustive vs Partial: と implies the list is complete. For 'A, B, and other things' (a non-exhaustive list), use や instead.
• ・Mutual Action: Used with verbs that require two parties (結婚する marry, 喧嘩する fight, 会う meet): 彼と結婚する (marry him).
• ・Quotative Particle: The と before 思う (think) and 言う (say) is the same particle, packaging the preceding clause as a single reported concept.

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones と is tested against.

• は (wa) — Topic & Contrast Particle
• が (ga) — Subject Marker & Exhaustive Listing
• を (o) — Direct Object & Traversal
• に (ni) — Target, Time, and Existence Location
• で (de) — Context of Action (Location, Means, Condition)
• か (ka) — Question, Or, and Uncertain Identity
• の (no) — Possession, Modification, & Nominalization
• も (mo) — Also, Too, Both/And, Emphasized Quantity